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Prediction of Carbofuran Degradation Based on the Hydroxyl Radical’s Generation using the FeIII impregnated N doped-TiO2/H2O2/Visible LED Photo-Fenton-like Process
摘要： Hydroxyl radicals (?OH) are the dominant reactive species during most photocatalytic reactions. Therefore, ?OH generation as an index could be beneficial in comparing the obtained results in different experimental setup designs, thereby providing new insights for understanding the photocatalytic mechanism. Heterogeneous Photo-Fenton like processes are one of the most effective technologies for degradation of organic pollutants through ?OH production. Nevertheless, kinetic models that take into account the dependence of the contaminant degradation on ?OH generation under homogeneous oxidant supply, are still limited in such processes. In this paper, a photo-Fenton like reagent (FeIII impregnated N-doped TiO2 (FeNT)/H2O2) involving both heterogeneous and homogeneous phases was employed for carbofuran (CBF) degradation, frequently used pesticide in many developing countries from the carbamate group. In addition, a commercial visible LED lamp (Vis LED) with high power output was utilized as an innovative and efficient visible light source to simulate solar energy. Accordingly, a new kinetic model was proposed to predict CBF degradation in the FeNT/H2O2/Vis LED process under high Vis LED light intensities based on intrinsic reaction parameters, including the Vis LED light intensity, FeNT dosage, initial H2O2 concentration, and ?OH generation. The developed model was verified and validated successfully under various reaction conditions. However, a standard error ranging from 3 % to 15% was observed at extreme cases such as high [FeNT] and I or low [H2O2]0 when comparing model predictions and experimental results. This is due to the use of averaged conditions to forecast the rate constants.
关键词： Fe-N doped TiO2,Hydroxyl radicals,kinetic modeling,Carbofuran,Visible LED,impregnation
更新于2025-09-16 10:30:52
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Treatment of Trichloroethylene with Photocatalyst-Coated Optical Fiber
摘要： In this present study, we investigated the effect of photocatalyzation on the degradation of trichloroethylene (TCE) in the aqueous phase by a photocatalyst-coated plastic optical fiber (POF). Two light-emitting diodes (LEDs) with low light intensity were used as the light source and TiO2 and ZnO were used as photocatalysts, which were characterized by scanning electron microscope (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). The para-chlorobenzoic acid (pCBA) was used as the hydroxyl radical probe for kinetic study and for the calculation of hydroxyl radical conversion rate (ROH,UV ). Experimental results show that POF coated with TiO2 exhibited higher degradation efficiency of TCE in basic solution, but POF coated with ZnO performed better in acidic solution. The increase of coating times resulted in the decrease in degradation efficiency of TCE due to increased thickness of the photocatalyst layer. The enhancement of light intensity contributed to the improvement of photocatalytic treatment efficiency. The ROH,UV for TiO2 and ZnO coated POF increased from 2 × 103 to 8 × 103 M s cm2 mJ?1 and from 8 × 102 to 2 × 103 M s cm2 mJ?1, respectively, as the pH increased from 4 to 10.
关键词： trichloroethylene (TCE),optical fiber,photocatalysis,groundwater,hydroxyl radical
更新于2025-09-12 10:27:22
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Protective characterization of low dose sodium nitrite on yak meat myoglobin in a hydroxy radical oxidation environment: Fourier Transform Infrared spectroscopy and laser Micro-Raman spectroscopy
摘要： The effect of NaNO2 in hydroxyl radical-mediated oxidative damage of yak meat myoglobin was investigated. Laser micro-Raman spectroscopy and Fourier Transform Infrared spectroscopy were used to assess protein (carbonyls, total sulfhydryl and Disulfide bonds) oxidation, atomic (or molecular) interactions and secondary structural changes. The addition of NaNO2 during the oxidation of myoglobin significantly reduced the content of carbonyl and disulfide bonds and protected the sulfhydryl groups from hydroxyl radical oxidation (P < 0.05). There was no significant difference in the secondary structure of myoglobin between the control group and the SN treatment group(P > 0.05). At the same time, NaNO2 had an inhibitory effect on the expansion of the hemoglobin center size and the transition of Fe from a low spin state to a high spin state caused by radical-oxidized. These findings suggest that NaNO2 has potential for treatment effects in a hydroxyl radical-oxidized myoglobin.
关键词： Secondary structure,Hydroxyl radical,Raman spectroscopy,NaNO2,Myoglobin
更新于2025-09-11 14:15:04
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Water Dissociation and Hydroxyl Ordering on Anatase
摘要： We studied the interaction of water with the anatase TiO2e001T surface by means of scanning tunneling microscopy, x-ray photoelectron spectroscopy, and density functional theory calculations. Water adsorbs dissociatively on the ridges of a (1 × 4) reconstructed surface, resulting in a (3 × 4) periodic structure of hydroxyl pairs. We observed this process at 120 K, and the created hydroxyls desorb from the surface by recombination to water, which occurs below 300 K. Our calculations reveal the water dissociation mechanism and uncover a very pronounced dependence on the coverage. This strong coverage dependence is explained through water-induced reconstruction on anatase TiO2e001T-e1 × 4T. The high intrinsic reactivity of the anatase TiO2e001T surface towards water observed here is fundamentally different from that seen on other surfaces of titania and may explain its high catalytic activity in heterogeneous catalysis and photocatalysis.
关键词： x-ray photoelectron spectroscopy,scanning tunneling microscopy,anatase TiO2,hydroxyl ordering,density functional theory,water dissociation
更新于2025-09-10 09:29:36
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Preparation of Nb2O5-decorated hierarchical porous ZnO microspheres with enhanced photocatalytic degradation of palm oil mill effluent
摘要： In the present work, Nb2O5-decorated hierarchical porous ZnO microspheres (ZnO/Nb2O5) were successfully prepared through a facile surfactant-free method. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller surface area analyses. Under UV light irradiation, the ZnO/Nb2O5 composites degraded palm oil mill effluent (POME) efficiently and demonstrated much higher photocatalytic activity compared to those of pure ZnO and Nb2O5. The enhanced photocatalytic degradation performance of ZnO/Nb2O5 composites was attributed to the high charge separation efficiency and hydroxyl radical generation ability as verified by the photoluminescence spectra. Phytotoxicity test upon the POME degradation over ZnO/Nb2O5 photocatalysis considerably decreased through the measurement of radicle lengths of Vigna radiata. Moreover, the ZnO/Nb2O5 composites were reused several times without appreciable loss of activity. This work revealed that the as-prepared ZnO/Nb2O5 composites have great potential for practical applications in the field of wastewater treatment.
关键词： Nb2O5-decorated hierarchical porous ZnO microspheres,Photocatalytic degradation,Charge separation efficiency,Palm oil mill effluent,Hydroxyl radical generation
更新于2025-09-10 09:29:36
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A quantitative XPS examination of UV induced surface modification of TiO2 sorbents for the increased saturation capacity of sulfur heterocycles
摘要： UV pretreatment has proven effective in enhancing the sulfur heterocycle specificity and saturation capacity of TiO2 adsorbents. Previous efforts in our laboratory have shown this effect to persist for over two weeks and were attributed to increased densities of surface hydroxyl groups as assessed by XPS and FTIR evaluations. This paper presents further evidence of the previous assertion by tracking the UV-induced conversion of adsorbed water and lattice oxygen into surface hydroxyls as monitored by XPS. Two different commercial TiO2 adsorbents (@ 163 and 70 m2/g) were investigated at various hydration levels as determined by TGA. Deconvolution of the XPS spectra demonstrated both the qualitative nature and quantitative conversion of adsorbed water and lattice oxygen according to the following stoichiometry, where one lattice oxygen is converted into two surface hydroxyls. Eight different reaction cases were examined using the 163 and 70 m2/g supports at four different hydration levels each. The measured stoichiometry for the above-noted conversion varied from 1.83 to 2.15 with an average value of 1.98 and a standard deviation of 0.10. Samples removed from the XPS chamber and stored in laboratory conditions showed that photo-generated surface hydroxyls could persist for over two weeks with or without handling.
关键词： XPS,TGA,Hydroxyl group,Titanium dioxide,UV,Photo-assisted adsorptive desulfurization
更新于2025-09-10 09:29:36
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Highly efficient total nitrogen and simultaneous total organic carbon removal for urine based on the photoelectrochemical cycle reaction of chlorine and hydroxyl radicals
摘要： Urine is a major nitrogen and COD source and threatens the aqueous environment, leading to eutrophication and energy consumption. However, the conventional technologies encounter the bottleneck due to the high load of nitrogen and organics in urine. Here we propose an innovative idea for complete transformation of urea-nitrogen to N2 and simultaneous degradation of organics to CO2 with the assistance of chlorine and hydroxyls radicals (Cl? and HO?) in photoelectrochemical cell system. This idea reveals circulation process of these two radicals: photoexcited holes from WO3 anode oxidize chloride and hydroxyl ions to Cl? and HO? radicals under illumination, these radicals convert urea-nitrogen to N2 or slight nitrate, and then slight nitrate is selectively reduced to N2 on a novel Pd/Au modified porous metallic sheet. TN analysis of a simulated urea solution of 30 mg L-1 demonstrated that N2 and CO2 are the primary oxidation products of the urea, and the urea-N was completely stripped (99.45%) in 90 min. Meanwhile, with the detection of EPR spectrum, organics can be transformed to CO2 by OH? in this cyclic system. Significantly, the feasibility of actual urine treatment was also investigated, indicating great denitrification efficiency (99.37%) and TOC removal efficiency (50.91%), respectively. This work sheds light upon a new economical, efficient, and environment-friendly means of urine sewage treatment.
关键词： urine,hydroxyl radicals,denitrification,chlorine radicals,photoelectrochemical
更新于2025-09-09 09:28:46
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Degradation of dimethyl phthalate using a liquid phase plasma process with TiO2 photocatalysts
摘要： The liquid phase plasma (LPP) method with a TiO2 photocatalyst and hydrogen peroxide was used to decompose dimethyl phthalate (DMP). As the applied voltage, pulse width, and frequency were increased, the rate of decomposition was increased and the decomposition rate was 63% for 180 min under plasma optimum conditions. The addition of TiO2 photocatalyst and hydrogen peroxide increased the DMP decomposition reaction rate, but an excess cause a decrease in decomposition rate due to a decrease in conductivity, blocking of ultraviolet light, and scavenger effect. When the TiO2 photocatalyst and hydrogen peroxide were used together, the decomposition reaction rate of DMP was greatly improved by using LPP single process alone. Also, when all the processes were used at the same time, the decomposition reaction rate was improved to about 2.8 times. DMP undergoes bond cleavage and ultimately decomposes into CO2 and H2O via dimethyl 4-hydroxyphthalate and methyl salicylates due to hydroxyl radicals and various active species generated by the LPP reaction.
关键词： Synergy effect,Hydrogen peroxide,Hydroxyl radicals,Decomposition rate,Degradation reaction pathway
更新于2025-09-09 09:28:46
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pHydroxyl decorated g-C3N4 nanoparticles with narrowed bandgap for high efficient photocatalyst design
摘要： Zero-dimensional graphitic carbon nitride nanoparticles (0D g-C3N4 NPs) possess the advantages of non-toxicity, metal-free, and rich surface catalytic active sites. However, the complex preparation process, wide bandgap structure, easily particle aggregation and rapid carriers’ recombination still limit their development in photocatalysis. Herein, these issues are addressed by synthesizing a novel hydroxyl (-OH) modified g-C3N4 NPs with a simple hydrothermal method without using any etching agents. Besides the high hydrophily and small particle size, the -OH decorated 0D g-C3N4 NPs possess obvious narrowed bandgap and high reduction potential. To further improve their dispersity and carriers’ separation rate, 0D/3D g-C3N4 NPs/ZnS type II heterojunction is fabricated, which simultaneously improves the hydrophily, passivates the surface defects and extends the sunlight absorption range of ZnS. As a result, a high and cyclable photocatalytic activity of 112 μmol h-1 (5.6 mmol h-1 g-1) is achieved under visible light irradiation without any co-catalysts, which is 140 times higher than that of pure ZnS and much better than the pure 0D g-C3N4 NPs. A systematic study of photocatalytic mechanism is proposed by combining the theoretical calculations and experimental results. This work offers a new sight for the design of 0D g-C3N4 NPs based photocatalysts for H2 production.
关键词： g-C3N4 NPs,Narrowed bandgap,Hydroxyl,Hydrogen,Photocatalysis
更新于2025-09-09 09:28:46
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Effects of mechanical stretching, desorption and isotope exchange on deuterated eucalypt wood studied by near infrared spectroscopy
摘要： Deuterium exchange combined with near infrared spectroscopy was used to study the roles of accessible and inaccessible cellulose in the load transfer of eucalyptus wood. Monitoring the drying process helped to assign bands of deuterated wood samples. Polarized NIR spectra of protonated and deuterated samples confirmed that inaccessible hydroxyl groups in eucalyptus wood were preferably oriented in the longitudinal direction. The spectral changes on NIR spectra caused by mechanical strain could be highlighted by averaging loading and unloading cycles to compensate for effects of desorption and isotope re-exchange due to environmental fluctuations. After deuteration, the bands affected by mechanical strain at around 6420, 6240 and 4670 cm-1, which had been assigned to hydroxyl groups in cellulose, remained at these positions, suggesting the inaccessible cellulose fraction was the main load-bearing component in wood. A small band at around 4700 cm-1 responding to mechanical strain, becoming visible in the deuterated spectra, indicated that accessible hydroxyls also contributed to the load transfer. Furthermore, the measurements confirmed previous reports of moisture adsorption of wood under tensile stress.
关键词： accessibility,tensile strain,deuterium oxide,cellulose,Eucalyptus regnans,dichroic ratio,hydroxyl groups
更新于2025-09-04 15:30:14